1. Field of the Invention
This invention relates to a device for spreading floor tile bonding material, and more particularly this invention relates to an adjustable device for spreading floor tile mortar at a predetermined thickness over a predetermined area of sub-flooring in an efficient and uniform manner; the device further being adjustable such that the device is capable of filling the spaces between the tiles with grout.
2. Description of the Prior Art
Ceramic flooring tiles are bonded to a variety of subfloors using bonding material including thin set mortar and grout. The term thin set mortar is used to describe the method of installing tiles with bonding material that is usually 3/32 of an inch to 1/8 of an inch in thickness. In other installations, a mortar bed up to two inches in thickness facilitates accurate slopes or planes in finished tile work on floors and walls. Portland Cement Mortar, comprising a mixture of Portland cement and sand, is suitable bonding material for most surfaces in ordinary types of installations.
Portland Cement is the base for most grout and is modified to provide specific qualities such as whiteness, mildew resistance, uniformity, hardness, flexibility and water retentiveness. Non-cement based grouts such as epoxies, furans and silicone rubber offer properties not possible with cement grouts.
Typically, bonding material is spread on an underlying sub-floor using a hand trowel. Hand trowels typically incorporate a trowel blade having serrated edges in the form of a square or sawtooth wave. Trowels are specially sized for spreading a particular thickness of bonding material wherein a larger square wave configuration is used for spreading a thick layer of mortar, and a smaller square wave configuration is used for spreading thinner layers of mortar.
It is very important that the mortar is spread evenly at a predetermined thickness for a given type of ceramic tile for installation. Obtaining an even layer of bonding material requires a high degree of skill on the part of the installer. In addition, because mortar begins to set or cure, the installer typically applies mortar over a relatively small area, subsequently changing over to a tile laying mode and installing the tile over the freshly mortared surface.
Since spreading mortar evenly and efficiently over a sub-floor surface is highly important and requires skill, and since frequent changeover from mortar spreading to tile laying is inefficient, a number of devices have been developed to improve the spreading process.
For example, U.S. Pat. No. 5,319,825 issued to Fanning on Jun. 14, 1994, discloses a concrete trowel extension. The extension has a flat upright frame with a pair of handles at the top for operating the frame and a trowel. A trowel is secured to the bottom of the frame by an adjustable clamp. The invention is directed toward a combined system including an extension on a conventional trowel that permits the user to apply pressure more accurately.
U.S. Pat. No. 4,723,869 issued to Dragich on Feb. 9, 1988, discloses a long-handled trowel with adjustable weights. The invention includes a trowel having a blade assembly, a reinforcing rib base mounted on the trowel's upper surface, and a handle pivotally connected at one end portion to the blade assembly such that an operator can move the blade member over the surface from a remote location. In addition, the invention contemplates adjustable weights which can be selected, added to or taken away from the blade assembly to vary the effective weight of the trowel. In this invention, the adjustable weights do not adversely affect the flexibility of the trowel blade proximate its edge portion such that a flexible blade serves to enhance the smoothness of the surface produced by the device.
Furthermore, floor tiles are typically installed in spaced relation such that a gap exists between adjacent tiles. While gap size varies depending upon the installation, 1/8 inch to 3/4 inch gaps are typical. After the tiles are set and bonded by the mortar, grout must be applied in a squeegee like manner such that these gaps are filled.
Thus, there still exists a need for a combination mortar and grout spreader having an adjustable trowel for spreading mortar over a sub-floor for efficiently spreading a large quantity of mortar in a single pass, and also used for filling the spaces between the tiles with grout.
In each of the prior art devices, however, pressure applied by the user on the trowel handle may adversely affect pressure on the trowel blade resulting in uneven spreading.
A further disadvantage with the prior art trowels is that the user must first provide a supply of mortar, typically by scooping the mortar using a hand trowel or other device from a bucket and then smoothing the mortar using the trowel. Therefore, should the user apply too much bonding material for a given area, the bed may be too thick. On the other hand, should the user not apply enough bonding material, the resulting bed may be too thin. Furthermore, should the user apply the bonding material by applying uneven pressure, the bed may be uneven. Thus there still exists a need for an automatic spreader wherein a measured quantity of bonding material may be placed for automatic distribution across the underlying sub-floor.